When using the worst case simultaneity factors to evaluate grid reinforcement needs, different simultaneity factors are used to dimension LV components (LV lines and MV/LV transformers) and MV components. Currently, to dimension the LV components we run a power flow for the whole MV grid (including all underlying LV grids) using the simultaneity factors for the LV. However, this is not quite correct, as the voltage at the MV side of the MV/LV transformers should be calculated using the MV simultaneity factors. Since MV simultaneity factors are mostly smaller than LV simultaneity factors, the voltage rise/drop in the MV is at the moment overestimated. But since we consider the relative voltage rise/drop to determine grid expansion needs, the effect shouldn't be too high. If we change the grid reinforcement to use the voltage at the MV side of the MV/LV transformers calculated using the MV simultaneity factors, it would require to run the power flow and grid reinforcement separately for every LV grid, in order to fix the voltage at the MV side. It is thus a larger change.
When using the worst case simultaneity factors to evaluate grid reinforcement needs, different simultaneity factors are used to dimension LV components (LV lines and MV/LV transformers) and MV components. Currently, to dimension the LV components we run a power flow for the whole MV grid (including all underlying LV grids) using the simultaneity factors for the LV. However, this is not quite correct, as the voltage at the MV side of the MV/LV transformers should be calculated using the MV simultaneity factors. Since MV simultaneity factors are mostly smaller than LV simultaneity factors, the voltage rise/drop in the MV is at the moment overestimated. But since we consider the relative voltage rise/drop to determine grid expansion needs, the effect shouldn't be too high. If we change the grid reinforcement to use the voltage at the MV side of the MV/LV transformers calculated using the MV simultaneity factors, it would require to run the power flow and grid reinforcement separately for every LV grid, in order to fix the voltage at the MV side. It is thus a larger change.